Conventionally, to achieve advanced services, it has been attempted to assign detailed attribution information to individual data. On the other hand, an attempt has been considered to make use of relationships among data in services (see Non-Patent Document 1). Especially, a social relationship, such as, e.g., a relationship among persons and a relationship between a context of person movements and locations has been drawn attention, and the relationship of such data is shown as a relationship graph.
The relationship graph represents, as shown in FIG. 10, objects, such as, e.g., persons, goods, places, and contents, as nodes, and represents the presence or absence of the mutual relationship among these objects by links. Further, the strength of the relationship between nodes directly connected with each other is given by a link length, and the strength of the relationship between nodes connected via other nodes is given by a path length. For this reason, when a certain node is selected as a reference point node, the relationship of the certain node to the reference point node is determined by the network graph structure of the path from the reference point node to the certain node.
By using the information observed in the real world or online as an input source, the object group contained in the input source is created as a node. Further, a link between nodes is also created, and therefore a small relationship graph (subgraph) is created.
Further, by connecting a plurality of subgraphs via a common node, a large one relationship graph is created and stored in a database (see Patent Document 1). In connecting them, when there exists the same link in an overlapped manner, the link length becomes shorter.
Further, a relationship graph stored in a database is referred to by and utilized in various applications. In cases where a relationship graph of persons only is formed using information of SNS (Social Networking Service) as an input source, even if there is no direct link with a certain person, it is possible to present (recommend) another person having a small path length as a future friend. For example, in an e-commerce (electronic commerce) by a mobile terminal, in cases where a relationship graph is formed based on a visit history to places and a purchase history of goods, when a certain consumer visits a certain place, it is possible to recommend goods having a small path length from the consumer and the place on the relationship graph.